1. Field of the Invention
The present disclosure relates to heat exchangers, and more particularly to counterflow heat exchangers.
2. Description of Related Art
Heat exchangers such as, for example, tube-shell heat exchangers, are typically used in aerospace turbine engines. These heat exchangers are used to transfer thermal energy between two fluids without direct contact between the two fluids. In particular, a primary fluid is typically directed through a fluid passageway of the heat exchanger, while a cooling or heating fluid is brought into external contact with the fluid passageway. In this manner, heat may be conducted through walls of the fluid passageway to thereby transfer thermal energy between the two fluids. One typical application of a heat exchanger is related to an engine and involves the cooling of air drawn into the engine and/or exhausted from the engine.
Counterflow heat exchangers include layers of heat transfer elements containing hot and cold fluids in flow channels, the layers stacked one atop another in a core, with headers attached to the core, arranged such that the two fluid flows enter at different locations on the surface of the heat exchanger, with hot and cold fluids flowing in opposite directions over a substantial portion of the core. This portion of the core is referred to as the counterflow core section. A single hot and cold layer are separated, often by a parting sheet, in an assembly referred to as a plate. One or both of the layers in each plate contains a tent fin section that turns the flow at an angle relative to the direction of the flow in the counterflow fin section in the center of the plate, such that when the plates are stacked together into a heat exchanger assembly, both hot and cold fluid flows are segregated, contained and channeled into and out of the heat exchanger at different locations on the outer surface of the heat exchanger.
This counterflow arrangement optimizes heat transfer for a given amount of heat transfer surface area. However, counterflow heat exchangers require a means to allow the flow to enter and exit the counterflow portion of the heat exchanger that also segregates the hot and cold fluids at the inlets and outlets of the heat exchanger; this is typically achieved with tent fin sections at an angle relative to the counterflow core fin section. To maintain practical duct sizes to channel fluid to and from the heat exchanger, a narrow tent section width is desirable; however, because a minimum distance between fins must be maintained throughout the core and tents for structural reasons, pressure drop through the tents of a counterflow heat exchanger is often undesirably high, resulting in an undesirably large heat exchanger volume and weight.
Such conventional methods and systems have generally been considered satisfactory for their intended purpose. However, there is still a need in the art for improved heat exchangers with reduced pressure drop through the tent sections. The present disclosure provides a solution for this need.